systemd.bbclass: enable all services specified in ${SYSTEMD_SERVICE}
This has been the traditional way of enabling systemd services.
It may conflict with presets feature, but other layers, image classes
and recipes add services to be enabled using SYSTEMD_SERVICE
variable also with read-only rootfs, e.g. IMAGE_FEATURES has
stateless-rootfs and systemd_preset_all task is not executed.
Fixes startup of custom services from our recipes using custom
image classes with various BSP layers. In the worst case even
serial console getty service wasn't starting due to dependency
no not enabled services.
Signed-off-by: Mikko Rapeli <mikko.rapeli@bmw.de> Cc: Peter Kjellerstedt <peter.kjellerstedt@axis.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
